The present application relates to a composite dielectric material for use in semiconductor devices and a method of forming a composite dielectric material. More particularly, the present application relates to a composite dielectric material including carbon nanotubes (hereinafter “CNTs”) randomly dispersed within a low dielectric constant dielectric material matrix and a method of forming such a composite dielectric material.
The continuous shrinking in dimensions of electronic devices utilized in ultra large scale integrated (ULSI) circuits in recent years has resulted in increasing the resistance of the interconnect metallization as well as increasing the capacitance of the intralayer and interlayer dielectric material. This combined effect increases signal delays in ULSI electronic devices. In order to improve the switching performance of future ULSI circuits, low dielectric constant (k) dielectric materials, and particularly those with a dielectric constant significantly lower than silicon dioxide, are needed to reduce the capacitance.
Low k dielectric materials are typically porous and hence wet chemical or gaseous species can penetrate into the pores of the low k dielectric material affecting the chemical nature of the film and degrading the electric properties. The mechanical strength of the low k dielectric material is also degraded, resulting in increased cracking during mechanical processing. There thus exists a need to produce low k dielectric materials with enhanced mechanical strength while retaining or improving their electrical properties.
In other methods, the prior art places CNTs on a substrate by first functionalizing the CNT and then placing the CNT directly on the substrate. However, such methods result in a low density of CNTs on the surface.
When present in films, CNTs are generally vertical and attached to substrates. These films generally exhibit low mechanical strength in the horizontal direction. Furthermore, the prior art vertical directional growth of the CNT with continuous tube growth from the bottom up can enable moisture to penetrate from top to bottom, or a contaminant to become trapped in the CNT during its exposure to various processing and fabrication environmental conditions. This moisture and/or trapping of contaminants will lead to a degradation of the film's properties and subsequently result in poor electronic device quality and reliability.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.